Method of preparing aminodithiothiazoles



United States Patent 3,133,920 METHOD OF PREPARING AMINODITHIO-THIAZOLES Albert F. Hardman, Northampton Township, Summit County, Ohio,

This invention relates to 2-(4-morpholinyl-dithio) thiazoles and to amethod of making these materials.

Morpholinyl-dithio thiazoles are powerful accelerators of vulcanizationof rubber. These materials are particularly useful in compositionscontaining rubber in which a potent, delayed-action, non-scorchingaccelerator is needed to promote curing of the rubber.

The compounds with which this invention is concerned are the2-(4-morpholinyl-dithio) thiazoles of the following general structure:

CHE-CH2 \O G 's-C62 in which R is an azole selected from the groupconsisting of Z-thiazoles and 2-aryl thiazoles.

According to this invention, 2-(4-morpholinyl-dithio) thiazoles areprepared by reacting an azole sulfenamide with morpholine and sulfur.

The reaction appears to proceed according to the following equation inwhich N,N-diisopropyl-2-benzothiazolesulfenarnide is used as arepresentative starting material.

CH (CH3) 2 CHgCH CSN H-N O S \s CH 011m OH -CH;

N i clan-on amon 0-8 s N O HN S CHz-C 2 CH 3) 2 The practice of theinvention is illustrated by the following representative examples.

Example 1 ing a melting range of l34135 C. was obtained. Analysis showedthe product to be 2-(4-morpholinyl-dithio) benzothiazole of 97.7%purity.

Example 2 Twenty-seven grams of N-cyclohexyl-Z-benzothiazolesulfenamide, 3.5 grams of sulfur, 9 grams of morpholine and 75milliliters of methanol were placed in a small three-necked flaskequipped with a stirrer and a reflux condenser. The mixture was stirredand refluxed. After about five minutes, upon seeding, fibrous crystalsbegan to separate. The mixture was refluxed about ten minutes longer,then cooled and filtered. The product was then washed with coldmethanol. Twenty-three and five tenths grams of crystalline materialhaving a melting range of 13 51 3 6 C. were obtained. 98.6 2-(4-morpholinyl-dithio) Example 3 Twenty-seven grams ofN,N-diisopropyl-2-benzothiazole sulfenamide, 3.5 grams of sulfur, 9grams of morpholine and milliliters of methanol were placed in athree-necked flask equipped with a stirrer and a reflux condenser. Themixture was stirred and refluxed. Crystals began to separate after aboutone hour. After 1 /2 hours the mixture was cooled, filtered, and thecrystals were Washed with cold methanol. Twenty grams of a crystallinematerial having a melting point of 132 C. were obtained. Analysis showedthe material to be 2-(4- morpholinyl-dithio) benzothiazole.

The material analyzed benzothiazole.

Example 4 Twenty-four grams of N-tertiary butyl-Z-benzothiazolesulfenamide, 3.5 grams of sulfur, 9 grams of morpholine and 75milliliters of methanol were stirred in a small flask at roomtemperature for 6 /2 hours. The original suspension slowly dissolved.After about an hour, crystals of the product began to separate. A yieldof 24.5 grams of product having a melting range of l29l32 C. wasobtained.

The examples above illustrate the invention with particular respect tothe preparation of 2-(4-morphol1nyldithio) benzothiazole. Othermorpholinyl dithio thiazoles can be prepared by similarly reacting otherazole sulfenamides with morpholine and sulfur. sulfenamides useful inthe process of this invention can be represented by the structuralformula R2 in which R represents a 2-thiazole nucleus and R and R arethe same or different members selected from the group consisting ofhydrogen, cyclohexyl radicals and alkyl radicals containing from 1 to 5carbon atoms, and the sum of the number of carbon atoms of R +R is aninteger from 1 through 8. Representative examples of these sulfenamidesare:

Z-thiazole sulfenamide Z-benzothiazole sulfenamide 2-naphtholthiazolesulfenamide N-methyl-Z-thiazole sulfenamide N-methyl-4-methyl-2-thiazolesulfenamide N-methyl-4-ethyl-2-thiazole sulfenamideN-methyl-2-benzothiazole sulfenamide N-ethyl-Z-thiazole sulfenamideN-ethyl-4-methyl-2-thiazole sulfenamide N-ethyl-4-ethyl-2-tl'iiazolesulfenamide N-ethyl-Z-benzothiazole sulfenamide N,N-dimethyl-2-tl1iazolesulfenamide N,N-dimethyl-4-methyl-2-th iazole sulfenamideN,N-dimethyl-4-ethyl-2-thiazole sulfenamide N,N-dimethyl-2benzothiazolesulfenamide N,N-dimethyl-2-tetrahydrobenzothiazole sulfenamideN,N-diethyl-2-thiazole sulfenamide N,N-diethyl-4-methyl-2-thiazolesulfenamide N,N-diethyl-4-ethyl-Z-thiazole sulfenamideN,N-diethyl-2-benzothiazole sulfenamide N,N-diisopropyl-Z-benzothiazolesulfenamide N,N-dibutyl-Z-benzothiazole sulfenamideN,N-diethyl-Z-tetrahydrobenzothiazole sulfenamideN,N-dipropyl-2-thiazole sulfenamide N,N-dipropyl-4-methyl-2-thiazolesulfenamide N,N-dipropyl-4-ethyI-Z-thiazole sulfenamideN,N-dipropyl-Z-benzothiazole sulfenamideN,N-dipropyl-Z-tetrahydrobcnzothiazole sulfenamideN,N-dibutyl-2-thiazole sulfenamide N-methyl, N-butyl-4-methyl-2-thiazolesulfenamide N-rnethyl, N-butyl-4-ethyl-2-thiazole sulfenamide N-methyl,N-butyl-2-benzothiazole sulfenamide N-cyclohexyl-2-benzothiazolesulfenamide N-methyl, N-butyI-Z-tetrahydrobenzothiazole sulfenamidePiperidyl-Z-thiazole sulfenamide Piperidyl-4-methyl-2-thiazolesulfenamide Piperidyl-4-ethyl-2-thiazole sulfenamidePiperidyl-2-benzothiazole sulfenamidePiperidyl-2-tetrahydrobenzothiazole sulfenamide The examples illustratethe invention carried out in methanol as a solvent. Other solvents canbe used instead of methanol. Representative examples of such solventsare ethanol, isopropanol, normal propanol, benzene, toluene and xylene.The process of the invention can also be carried out without a solventbeing present by causing the materials to react in molten condition. Inthis case, when the amine of the sulfenamide is relatively volatile itcan be distilled off, under reduced pressure, if desired and the productobtained in practically pure state. When the amine of the sulfenamidehas a high boiling point, the product can be purified by leaching theamine out of the mixture with a solvent such as methanol or the productcan be purified by dissolving it in a solvent and then crystallizing it.

The temperature at which the reaction is carried out is not critical,but it is desirable to use a temperature that will give reasonably fastreaction rates so that the process can be economically carried out. Formost efiicient use of the reactants, one mol of the sulfenamide is usedto about one mol of morpholine and one mol of sulfur, but an excess ofany of the reactants can be used as desired.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

I claim:

1. The method of preparing a 2-(4-morpholinyl dithio) thiazole whichcomprises reacting sulfur and morpholine with a sulfenamide of thegeneral formula in which R is a 2-thiazole radical and R and R are thesame or different members selected from the group consisting ofhydrogen, cyclohexyl radicals, and alkyl radicals containing from 1 to 5carbon atoms, and the sum of the number of carbon atoms of R plus R isan integer from 1 through 8.

2. The method of claim 1 in which the sulfenamide used is2-benzothiazole sulfenamide.

3. The method of preparing a 2-(4-morpholinyl dithio) thiazole whichcomprises reacting sulfur and morpholine with a sulfenamide of thegeneral formula in which R is a 2-thiazole radical and R and R are thesame or different members selected from the group consisting ofhydrogen, cyclohexyl radicals, and alkyl radicals containing from 1 to 5carbon atoms, and the sum of the number of carbon atoms of R plus R isan integer from 1 through 8, the reaction being conducted under refluxconditions in a solvent selected from the group consisting of methanol,ethanol, isopropanol, normal propanol, benzene, toluene, and xylene.

4. The method of preparing 2-(4-morpholinyl dithio) benzothiazole whichcomprises reacting N-cyclohexyl-Z- benzothiazole sulfenamide with sulfurand morpholine.

5. The method of preparing 2-(4-morpholinyl dithio) benzothiazole whichcomprises reacting N,N-diisopropyl- 2-benzothiazole sulfenamide withsulfur and morpholine.

6. The method of preparing 2-(4-morpholinyl dithio) benzothiazole whichcomprises reacting N-tertiary butyl- 2-benzothiazole sulfcnamide withsulfur and morpholine.

References Cited in the file of this patent UNITED STATES PATENTS1,544,687 Sebrell et al. July 7, 1925 2,273,321 Jones Feb. 17, 19322,382,793 Howland Aug. 14, 1945 2,779,761 Kibler Jan. 29, 1957 2,837,519Hardman June 3, 1958 FOREIGN PATENTS 711,236 Great Britain June 30, 1954

1. THE METHOD OF PREPARING A 2-(4-MORPHOLINYL DITHIO) THIAZOLE WHICHCOMPRISES REACTING SULFUR AND MORPHOLINE WITH A SULFENAMIDE OF THEGENERAL FORMULA